has anyone out there thought of taking the rear set of cats off before setting up dual exhaust? i have a buddy that had this done with his mustang and it made a huge difference in power and was much more throaty-souning. i crawled under mine today and noticed a sensor after the cat, can this be used if you get rid of the rear cats? will it cause any "check engine" lights to go crazy???????

 

just take a pipe (or broomstick etc)
and use it like a shovel
jam all the stuff in teh cat out
and u wont have to worry about getting braketag (some places check for cats)
and since theres nothing in them u will get the hp gain

 

That sensor checks the cat to see if it is working within specs. Removing the cat or punching it out will trip the check engine light.

 

Inside the cat is a ceramic like material that has 'millions' of tiny square holes through it. This gets 'super hot' and must burn more of the pollutants out of the exhaust. When I had my '86 Mustang GT with some straight through mufflers, a big chunk of this actually shot out of the tail pipe. I also had 2.5" mandrel bent tailpipes. Mustangs had the mufflers bolted to the "H" pipe, so I just took them off, and used a pipe to ram the back cats internals out. Just like radzer0 said. The Mustang did not have O2 sensors after the cats, so did not effect the computer/smog test. It actually passed with better numbers then with all four!

After I punched them out, I just started the engine and reved it up several times to blow the broken pieces out. Kept doing this until I heard no more rattleing. It sounded pretty cool without the mufflers, but I did bolt them back on. It made a big difference in power and sound. As I said, it still passed the "sniff" test. I later purchased a mandrel bent 2.5" "H" pipe from BBK that had two Hi Flo cats. A bit more power and sound came from this swap too. Traded the Stang before it's smog test, so don't know how they would have done.

I'd leave the ones on the F150 alone. For one thing you won't be able to get to the drivers side rear cat, as it's got a 90 degree bend in the pipe before it. From what I understand, these all have a form of Hi Flo cats anyway. Just go true duals from in front of the Y pipe. Mine has a sensor on the Y pipe itself, so if your's is similar, you'd have to cut it off after the sensor.



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1997 F150 4x4 Off Road, SuperCab, Short Box, 5.4, Royal Blue/Silver, K&N, Gibson SS, LT265/75/16 Wild Country APT's

 

what is there inside the catalytic converter that you are talking about"jamming it out"?
also if i rammed it out of there then how would i get the pieces out of there?

 

Mitchf150,
I did the exact same procedure on a 95 ford
I bought new. I used a long construction
crowbar to "ram" it out though. I still
have the truck today, along with my 98, and
the check engine light has never come on. It
did make the idle a tad rougher though, but
it was not that noticeable.

 

How did you get around the bend of the exhaust pipe on the drivers side?

 

His '95 only had 2 cats, and they are right in a tow with a little bend in between the two. When I had my '92 I was only runnin with the first cat, when I knocked the guts out of the second one it did not make anymore noise, and no horespower gain. So the first one was the restrictive one.